Telecommunications service providers and their customers monitor the speeds at which their customers can download data. These speeds are often a key part of advertising. The Federal Communications Commission (FCC) is similarly concerned with data speeds and has established a process to measure achievable data speeds for selected users. The process entails running a speed test on a customer's computer.
In the speed test, an agent on the customer's computer downloads a large file from a server for a predetermined time (e.g., a 20 second interval). During an interval after the connection has become stable (e.g., five seconds beginning from 10-15 seconds in the 20 second interval) the agent measures how many bytes arrived from the server and divides by the download time to get the download throughput in megabits per second (Mbps). The throughput should match the customer's provisioned data rate. For example, a customer provisioned at 25 Mbps should be able to run speed tests at 25 Mbps. In some instances, the speed test throughput will be less than the customer's provisioned data rate. This may be a result of congestion on a link that the customer shares with other traffic.